Waterproof Flexible Printed Circuit Board with Stepped Lamination

Solution Overview

Problem

Flexible printed circuit boards (FPCBs) in foldable electronic devices face challenges in maintaining flexibility and preventing the introduction of foreign substances, such as moisture or dust, when their layers are curved or deformed.

Innovation Solution

The implementation of a stepped lamination structure in the FPCB, where layers are laminated at different areas, combined with a sealing member and a waterproof member, prevents foreign substances from entering between the layers while maintaining the required shape and flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the plurality of layers are laminated on each other to prevent introduction of foreign substances, then waterproof/dustproof performance is improved, but flexibility is reduced and thickness increases

Engineering Contradiction:

Improvewaterproof/dustproof performanceVSAvoidflexibility

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The FPCB is divided into multiple sections with different lamination configurations: a first section with laminated layers for waterproofing, a second section with separated layers for flexibility and curving, and a third section with laminated layers for waterproofing. This segmentation allows different parts of the same FPCB to have different properties tailored to their functional requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sections of the FPCB have different lamination qualities: the first and third sections have laminated layers with adhesive layers to prevent foreign substance introduction, while the second section has separated layers to enable curving and flexibility. Each section's structure is optimized for its specific functional requirements.

Inventive Principle:

Principle #3Local quality

2Reliability

If the plurality of layers are laminated on each other to prevent introduction of foreign substances, then waterproof/dustproof performance is improved, but the thickness of the FPCB increases

Engineering Contradiction:

Improvewaterproof/dustproof performanceVSAvoidthickness

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The FPCB is divided into multiple sections with different lamination configurations: a first section with laminated layers for waterproofing, a second section with separated layers for flexibility and curving, and a third section with laminated layers for waterproofing. This segmentation allows different parts of the same FPCB to have different properties tailored to their functional requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of laminating all layers throughout the entire FPCB, the invention applies lamination only partially in specific sections where waterproofing is required. The adhesive layers are applied only in the first and third sections, not in the second section where flexibility is needed, thus avoiding excessive thickness increase.

Inventive Principle:

Principle #16Partial or excessive action

3Ease of operation

If the plurality of layers are separated from each other to be curved or bending some sections, then flexibility is improved, but foreign substances may be introduced between the layers

Engineering Contradiction:

ImproveflexibilityVSAvoidintroduction of foreign substances

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The FPCB is divided into multiple sections with different lamination configurations: a first section with laminated layers for waterproofing, a second section with separated layers for flexibility and curving, and a third section with laminated layers for waterproofing. This segmentation allows different parts of the same FPCB to have different properties tailored to their functional requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sections of the FPCB have different lamination qualities: the first and third sections have laminated layers with adhesive layers to prevent foreign substance introduction, while the second section has separated layers to enable curving and flexibility. Each section's structure is optimized for its specific functional requirements.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20250120015A1Flexible printed circuit board having waterproof structure and foldable electronic device including the same

Publication Date: 2025.04.10 SAMSUNG ELECTRONICS CO LTD

AI summary

An electronic device includes a first housing having a first through-hole, of which a first opening and a second opening are communicated with each other, and a second housing connected to the first housing to be rotatable. A flexible printed circuit board (FPCB) extends from the first housing to the second housing via the first through-hole. The FPCB includes a plurality of layers, a first sealing member disposed in the first through-hole and surrounding the FPCB, and a lamination part toward the first sealing member. A portion of a first layer and/or a second layer corresponding to the second lamination part includes at least one first valley extending from a surface that faces an adjacent layer in a lengthwise direction of the FPCB. The lamination part includes a first adhesive layer interposed between the first layer and the second layer and filling the at least one first valley.